Apparatus for handling a paste-like material containing a gas



May 8, 1962 APPARATUS FOR HANDLING A PASTE-LIKE MATERIAL CONTAINING AGAS J. KINZELMAN 3,033,123

Filed Dec. 19, 1957 /N VE N TOR.

O fig yaw/z ma ma ywwy A TTORNEVS.

United States Patent Office 3,033,123 Patented May 8, 1962 APPARATUS FORHANDLING A PASTE-LIKE MATERIAL CONTAINING A GAS Joseph Kinzelman,Northbrook, 111., assignor to Plastering Development Center, Inc.,Chicago, 111., a corporation of Illinois Filed Dec. 19, 1957, Ser. No.703,969

6 Claims. (Cl. 103-195) This invention relates to apparatus and methodfor handling a paste-like material containing a gas, and, moreparticularly, to that useful for pumping a substantially continuous anduniform stream of such material.

For many years, there has existed a problem in the handling andprovision of streams of paste-like materials containing gases such asplasters and other cementitious mixes, as for application to buildingwalls, ceilings, and the like. The problem revolves about thecompressible nature of the mix. The compressible nature of the mix stemsfrom the gas that it contains, the occluded gases being necessary toprovide suitable internal lubrication in the mix when it is handledprior to mechanical application.

The problem becomes especially acute when positive displacement devicesare employed to handle the Such devices, however, are preferred, sincethey can readily employ the high pressures needed to move sluggishstreams such as plasters, and the like. Where, for example, a dualcylinder and piston unit apparatus is employed, it has beencharacterized by uneven rates of discharge of the compressible material.The ordinary operation of such a device would have one cylinder pumpingwhile the other is discharging. However, because of the compressibilityof the mix, there is a hiatus between the commencement of the pumpingstroke and the actual discharge from the cylinder in which the pumpingstroke has commenced.

The above-referred-to hiatus produces an interruption in the flow ofpaste-like material which can be especially bothersome when the materialis being applied overhead. The decrease in flow may even result in thematerial not reaching the ceiling, but instead falling downwardly on theoperator. Thus, an apparatus embodying positive displacement mechanismsthat could overcome the problem of intermittent flow, would beespecially desirable.

It is an object of this invention to provide a novel method andapparatus which overcome the problem outlined above. :Another object isto provide an apparatus embodying positive displacement mechanisms thatprovides a substantially continuous and uninterrupted flow of materialof a paste-like character and containing a gas. Still another object ofthis invention is to provide an apparatus and method that are able toprovide a continuous and uniform flow of paste-like materials containinggases where successive batches or runs of the material contain varyingamounts of gas.

A further object is to provide an apparatus including three compressionchambers which cooperate to provide a positive flow of a paste-likematerial containing a gas but without the flow interruptions heretoforeconsidered implicit in such positive displacement structures. A stillfurther object is to provide apparatus of the character described in theobject set forth immediately above and in which a novel combination ofworking elements cooperate to provide a compact, rugged and superioroperating structure. Other objects and advantages of this invention willbe seen as this specification proceeds.

This invention will be explained in conjunction with an illustratedembodiment in the attached drawing, in which FIG. 1 is an elevationalview of an apparatus embodying the teachings of this invention;

FIG. 2 is an enlarged cross sectional view taken along the line 22 ofFIG. 1;

FIG. 3 is a cross sectional view taken along the line 3-3 of FIG. 2;

FIG. 4 is a schematic representation of the apparatus shown in greaterdetail in FIGS. 1-3.

In the illustration given, the numeral 10 designates generally acylindrical housing which includes two portions 11 and 12 separated byan intervening bulkhead 13 and closed at opposite ends by end covers 14and 15 located at the bottom and top ends as shown, respectively. Aplurality of tie rods 16 extend between the end plates 14 and 15 toprovide the rigid structure. Tie rods16 extend through arcuatelydisposed openings in the end plates and are secured in position by nuts17.

The casing 10 serves as a pump for gas-containing pastelike materialsuch as plaster or other cementitious compounds and, in the illustrationgiven, the lower portion of HG. l is provided with a paste inlet at 18and an outlet at the upper portion at 19, the outlet also being seen inFIG. 2. conventionally, inlet 18 may be communicated to a hopper andoutlet 19 communicated to a hose through which the paste-like materialis dispensed.

The structure provided in the upper portion of FIG.

' 1 and above end plate 15 which is designated generally by the numeral211 represents one form of apparatus for reciprocating a piston rodcarrying pistons within cylindrical housing 113.

Before proceeding with a detailed description of the various componentparts of the apparatus as can be seen in FIGS. 2 and 3, it is believedthat a general description of the mode of operation as can be betterappreciated from schematic representation in FIG. 4 will be helpful inunderstanding the invention and the elements employed in practising it.For that purpose, the following description is given.

In FIG. 4, there is seen a cylindrical casing corresponding to cylinder11 and which is designated in FIG. 4 as 111. A casing corresponding tocylinder 12 is designated in FIG. 4 by the numeral 112. A bulkhead isseen to exist between cylinders 111 and 112 and is designated by thenumeral 113. A piston 121 is reciprocably mounted within cylinder 112and a second piston designated 122 is re ciprocably mounted withincylinder 111. Pistons 121 and 122 are rigidly interconnected by means ofa common piston rod 123 and a second piston rod extends upwardly frompiston 121 and which is designated 124. Piston rod 124 is adapted to beconnected to a source of motive power for reciprocating the two pistons.Three check valves are seen in the schematic representation of FIG. 4.One check valve designated by the numeral 125 is located in the end wallof cylinder 111. A second check valve 126 is located in piston 122, anda third check valve is located in bulkhead 113 and is designated 127.Each of these check valves is so oriented as to permit flow of pastelikematerial only upward in the schematic illustration given. Thus, checkvalve 125 operates to permit only entry of paste into chamber orcylinder 111 from an external source such as is designated by thenumeral 118. Material passing through the apparatus of FIG, 4 issuesfrom cylinder 112 to outlet 119.

It is to be noted that the two pistons define three chambers which forthe sake of convenience will be designated by the capital letters A, Band C, chamber A being a chamber of variable internal volume defined bypiston 122 and the bottom end wall of cylinder 111, chamber B by piston122 and the top end Wall of cylinder 111 (i.e., bulkhead 113), andchamber C being defined by the bottom end wall of cylinder 112 (bulkhead113) and piston 121. When the piston assembly is at its lowermostposition, it starts moving upwardly and paste is drawn in through valve125. When the piston assembly (i.e.,

J pistons 121 and 122 and piston rods 123 and 124) reaches the extremetop position and thereafter starts downwardly, valve 125 closes andvalve 126 opens, and paste flows from chamber A into chamber B. Sincethe volume in chamber A is diminishing at a greater rate than the volumein chamber B is increasing due to the volume taken up by the piston rod123, the paste in communicated chambers A and B is compressed. Thiscompression occurs after one or two complete strokes of the pistonassembly, since the initial strokes merely fill the apparatus withpaste. Chamber B decreases in volume more rapidly than chamber Cincreases, so that when the piston assembly moves upwardly, a portion ofthe paste issuing from chamber B goes into chamber C to fill the samewhile the remainder of the paste issuing from chamber B flows throughoutlet 119. Optimum results can be obtained when chamber C has a maximuminternal volume change equal to one-half of the maximum internal volumechange of chamber B. In such a case, one-half of the paste is deliveredto outlet 119 on the upstroke (this issuing from chamber B) while thesame amount is delivered during the downstroke from chamber C. Departurefrom the indicated volumetric ratio can be compensated for by makingcorresponding changes in the time relationship for the up and downstrokes.

In the operation of the apparatus generally described above, the openingof valve 126 in piston 122 on the downstroke of piston 122 establishescommunication between chamber .A and chamber B, these two chambersthereby becoming one large chamber which is steadily reduced in grossvolume by the space occupied by piston rod 123. It is to be immediatelyappreciated that the farther piston 122 travels downwardly, the morepiston rod 123 is inserted into the larger chamber defined by chambers Aand B. Concurrently, chamber C is isolated by the closure of valve 127.The material in chamber C, therefore, is forced out through outlet 119because the volume of chamber C is decreased through the entry of piston121 thereinto. On the upstroke of the piston assembly, valve 126 closes,thereby isolating chamber A from chamber B while valve 127 opens toestablish communication between chamber B and chamber C. These twolast-mentioned chambers together form a large chamber which is steadilyreduced in gross volume because the increase in volume of chamber C issmaller than the decrease in volume of chamber B. In the specificillustration given, this is immediately apparent, since the diameter ofpiston 121 is smaller than the diameter of piston 122 and since they areconnected, the strokes are the same. The excess material in the largerchamber defined by chambers B and C is, therefore, forced out of outlet119. Concurrently with the communication of chambers B and C, chamber A,which is increasing in volume through the upstroke of piston 122, ischaracterized by a reduced pressure. This reduction in pressure allowsthe atmospheric pressure operating against the source of paste materialto open valve 125 and force material to flow into chamber A.

In operation, the downward movement of the piston assembly is stoppedwhen pressure developed within chamber B is just equal to that inchamber C. It is to be appreciated that an undesirable pulsation wouldoccur if the maximum pressure developed in chamber B exceeded that inchamber C, since then valve 127 would be opened on the downstroke ratherthan just the upstroke of the piston assembly and, therefore, paste fromboth chambers B and C would be delivered to outlet 119. A number ofdevices can be employed for this purpose. Schematically represented inFIG. 4 (the upper left-hand corner) is one such structure. There, thenumeral 130 designates an arm extending laterally from piston rod 124.Arm 130 is in sliding engagement with a guide rod 131 on which arepositioned collars 132 and 133 at the upper and lower portions,respectively. Rod 131 is reciprocably supported by valve housing 134,which in turn can be conveniently supported on cylinder 112. Valvehousing 134 contains suitable pressurized fluid-regulating means tocause reciprocation of the piston assembly. Thus, as piston 121 proceedsdownwardly, arm ultimately engages collar 133, signalling the regulatingmeans in housing 134 to reverse the travel of the piston assembly. Inthe same manner, engagement of arm 130 with the upper collar 132produces another change in the direction of travel of the pistonassembly. Collar 133 can be adjustably mounted on rod 131, permittingvariation of the stroke of the piston assembly for materials ofdifferent compressibilities. Although the operation of this assembly hasbeen set forth in terms of handling a paste-like material containing agas, it is to be appreciated that it serves equally well for positivelydisplacing other compressible materials requiring a substantially steadyflow.

As pointed out above, the setting of the collar 133 or otherstroke-limiting device, is dependent upon the compressibility of thepaste-like material being handled. A paste-like material containingrelatively little gas might be suitably compressed in chamber B by onlya partial downward movement of the piston assembly. Mixes with greatercompressibilities would, therefore, require a greater stroke on the partof the piston assembly.

Referring now to FIG. 2, an embodiment of the invention is seen that isthe counterpart of the schematic representation seen in FIG. 4. Forexample, in FIG. 2, cylinder 11 defines two compression chambers A belowpiston 22 and chamber B above piston 22. Cylinder 12 defines chamber Cand the counterpart of piston 121 of FIG. 4 is a hollow ram 21.

Focusing now on the bottom portion of FIG. 2 it is seen that end-plate14 is provided with an opening 14a extending therethrough which isclosed by a check valve designated generally by the numeral 25. Checkvalve 25 includes a rigid core portion 25a surrounded by a resilientportion 25b which are adapted to engage the inwardly tapered side wallof opening 14a. Valve 25 is also equipped with a stem- 25c which isguided along the axis of opening 14a by a guide bracket 25d secured toend-plate 14. Angle-shaped member 25:; serves as a stop for the downwardmovement of valve 25.

Proceeding upwardly in FIG. 2, the next element is piston 22 mounted onthe end of piston rod 23, piston 22 being slidably mounted withincylindrical housing 11. Threadedly atfixed to the end of piston rod 23is a piston carrier 22a which is a cylindrical-like fitting equippedwith outwardly-extending lug 22b which receives four bars 220 whichperform a dual purpose in that the they both support the piston body22:! and act as a guide for the piston check valve 26. Check valve 26,like check valve 25, is provided with a metallic core portion 26a, aresilient outer portion 26b, and a stem 26c. Stern 2150 slides in awasher assembly 26d which is equipped with laterally-extending arms 26awhich engage bars 22c and guides valve 26 along the axis of piston rod23 and opening 222 in piston body 22d which serve as a seat for valve26. Piston body 22d is provided with a suitable perimetric seal toinsure sealing engagement of piston body 22d with the inner wall ofcylinder wall 11.

At the upper end of cylinder 11, and connecting the same to cylinder 12,is bulkhead 13, which also serves to isolate one cylinder from the otherand provide communication therebetween by means of a check valvegenerally designated 27. As can be appreciated from a consideration ofFIG. 3, bulkhead 13 is provided with a plurality of openings 13aextending therethrough which are arcuate in form and disposed in acircular pattern. Bulkhead 13 is provided with a recess in the upperinterior portion as at 13b which provides a mounting for a valve seat13c which has openings therein aligned with openings 13a and bulkhead13. Valve 13c is secured to bulkhead 13 by a plurality of bolts 13d.Valve 13c and bulkhead 13 are beveled at their inner mating surfaces toprovide a V-shaped recess which receives and supports a seal 23a forpiston rod 23.

The moving element of valve 27 is essentially a cylindrical cageprovided by upper ring 27a, lower ring 27b, and connecting stem 27c.Stems 27c pass through openings 13a in bulkhead 13 and correspondingopening in valve 13 and in addition support a third metal ring 27d aboutwhich is positioned a resilient ring 27s. A valve structure of this typeis set forth in greater detail in the co-owned, copending application ofLloyd H. Hobson, Serial No. 709,300 filed January 16, 1958, now PatentNo. 2,949,928 and reference is hereby made to that application. Rings27a and 27b are provided with a cen: tral opening that permits a slidingfit with piston rod 23 and which permits rings 27a and 27b to act asglides to direct valve 27 along a path parallel to the axis of thepiston rod 23.

Piston rod 23 is equipped with a threaded recess 23b at the upper endthereof which receives a threaded projection 21b of ram 21, therebyrigidly connecting ram 21 and piston 22 in a manner analogous to theconnection between pistons 121 and 122 in FIG. 4.

The cylindrical housing which, with ram 21, defines chamber C, isprovided by cylinder 12 and outlet fitting 19a. Outlet fitting 19a isequipped with a laterally-extending bore 19 which serves as an outletfor paste-like material from chamber C. The upper end of outlet fitting19a is provided with a central opening 19b which permits reciprocationtherein of ram 21. The upper surface of outlet fitting 19a is beveledand, in cooperation with end-plate 15, provides a recess for the receiptand mounting of a ram seal 190.

Ram 21 is reciprocated by introducing a pressurized fluid on one side orthe other of a stationary piston 26a supported on a hydraulic piston rod20b (seen also in FIG. 1), piston 26a being slidably received within ram21. To force ram 21 downwardly, and hence the entire piston assemblyincluding piston 22, pressurized fluid is introduced through the hollowcentral portion of rod 2% while upward movement of ram 21 and the pistonassembly is etlected by introducing pressurized fluid against the upperside of piston 20a through inlet port 200. For this purpose, apressurized fluid such as oil can be conveniently used with conventionalvalving arrangements to apply pressure to one port while permitting adischarge from a second port, i.e., when fluid is introduced into port200, the hollow piston rod 20b is vented to a sump, or the like.

Providing an upper end closure for ram 21 is a cylinder end-fitting 21cwhich has a laterally-extending bore therein providing port 200. Fitting21c is threadedly connected with ram 21 and is provided with an axialbore permitting sliding movement of fitting 21c on piston rod 20b.Housed within the axial opening of fitting 210 is a packing gland 21dand confined therein by a flat gland retainer plate 21e suitablyanchored to fitting 21c.

Piston rod 2% is maintained in a position along the axis of cylinders'11 and 12 by the cooperation of base plate 28 and outlet fitting 19awhich are tied together by means of tie rods 29. These tie rods alsosecure seal 19c and end-plate 15. This structure insures that ram 21,which is slidably mounted on stationary piston 20a, will reciprocatealong the axis of cylinder 12.

The operation of the device shown in FIGS. 1-3 is analogous to theoperation of the schematic representation of a simplified device shownin FIG. 4. For example, upward movement of the piston assembly whichincludes piston 22, piston rod 23 and ram 21, induces a flow ofpaste-like material into chamber A through inlet port or opening 14a,valve 25 being open (its position opposite to the one shown). Upwardmovement of the piston assembly also results in the closing of checkvalve 26 in position 22 and the opening of check valve 27 in bulkhead 13so that a paste-like material contained in chamber B is transferred intochamber C which is expanding due to the retraction therefrom of ram 21.'However, the expansion of chamber 0' is insuflicient to accommodate allof the material discharged from chamber B to check valve 27, so that aportion of the material introduced into chamber C is released to outlet19. Upon downward movement of the piston assembly, check valve 27 isclosed so that the decrease in internal volume of chamber C due to thereceipt thereinto of ram 21 forces material previously contained inchamber C out of outlet 19, thereby maintaining a continuous stream ofthe desired paste-like material. Simultaneously with the dischargeeffectuated by the inward movement of ram 21 into chamber C, thedownward movement of piston 22 closes inlet check valve 25 and opens thecheck valve 26 in piston 22, thereby eflectuating a transfer ofpastelike material from chamber A into chamber B. The entrance of pistonrod 23 into the larger chamber defined by A and B causes compression ofthe paste-like material therein. Without such compression intermediatethe intake and discharge, there would occur the undesirable hiatus inflow characteristic of previously-employed posi tive displacementmechanisms.

As indicated above, a pressurized fluid can be employed to reciprocatehollow ram 21. The reciprocation of hollow ram 21 under suchcircumstances not only serves to discharge material from chamber C, butat the same time permits heat exchange to occur between the materialbeing pumped in chamber C and the pressurized fluid within hollow ram21. This is particularly true during the downward stroke of ram 21 (asseen in FIG. 2), since then the material in chamber C, in etfect, flowsalong the length of ram 21 which is stroking in an opposite direction toreach outlet 19. To aid in this heat exchange, ram 21 is constructed ofa thermally conductive material, preferably a metal such as steel. Theimportance of this heat-exchange can be appreciated from the fact thatconventionally employed hydraulic fluids such as the oils ordinarilyused for reciprocating ram 21, have a maximum operating temperature inthe range ISO- F. Because of this limitation, it has been the practicein the past to equip hydraulic systems with some means for cooling thepressurized fluid, since there is always a certain amount of powerapplied to the hydraulic system which is converted to heat energy. Thisheat energy, if undissipated, accumulates and, after a period, raisesthe temperature of the hydraulic fluid above the allowable range. Aconventional expedient, for example, is to pass the hydraulic fluidthrough an air-cooled radiator, or the like, to remove the undesirableheat. The problem of heat accumulation is further aggravated when thehydraulic system is employed to operate a device at less than maximumcapacity. For reasons of economy, the prime mover in the hydraulic fluidsystem is generally proportioned to operate at a rating equivalent tothe maxlmum operating characteristic of the device deriving power fromthe hydraulic system, and any lesser operatmg characteristic is normallyaccomplished by allowing part of the oil to return to the sump, or thelike, by bleeding it oif the high pressure output. Thus, whenever thedevice deriving power is operating at less than maximum, the excesspower put into the system is converted to heat, which also must bedissipated. For example, ordinarily, a hydraulic system employs a pumpas a prime mover, with the pump operating at constant output. In theillustration given, the pumping apparatus for plaster might often beoperated at less than maximum capacity, since there are manyapplications where the paste must be discharged at less velocity thanthat possible. In such a case, it is apparent that the hydraulic systemfluid would soon be heated above a tolerable value if some meansv Werenot provided to dissipate the heat.

In the practice of my invention, I have found that any heat introducedinto the pressurized fluid in the hydraulic pressure system employed toactuate ram 21 is rapidly d1ssipated through the wall of ram 21 into thestream of fluid material flowing from valve 27 providing the inlet tochamber C upwardly through chamber C and along the length of ram 21 andfinally discharging through outlet 19. It is to be appreciated thatadditional heat exchange can be conveniently obtained by elongating ram21 and chamber C correspondingly, with the further location of outlet 19a further distance from the inlet provided by valve 27.

The type of ram structure pictured in FIG. 2 also produces anotherdesirable result in the dissipation of heat from the hydraulic fluidpowering ram 21, in that ram seal 19c effectively clears the outersurface of the ram 21 of any adherent material. Once each cycle of themovement of ram 21, seal 19c literally scrapes off the adherentpastelike material so as to permit ram 21 to move into the mass ofpaste-like material in chamber C free of any heat-retarding layer. Thiscould be analo gized to the prevention of laminar flow of paste-likematerial in chamber C which would materially lessen heat transferbetween the pressurized fluid within ram 21 and the paste-like materialsurrounding ram 21 in chamber C.

In the illustration given, it is to be noted that heat transfer isachieved during both upward and downward strokes of ram 21. During thedownward stroke, the ram 21 is entering the body of paste-like materialconfined within chamber C because of the closing of valve 27. During theupstroke of ram 21, paste-like material continues to flow past the faceof ram 21, since the rate of decrease of chamber B is greater than therate of increase of chamber C and material continues to move towardoutlet 19.

- While in the foregoing specification an embodiment of the inventionhas been set forth in considerable detail for the purpose ofillustrating the invention in a manner that it may be readily practicedby those skilled in the art, it is to be appreciated that the inventionis susceptible of many variations while still being within the spiritand principles of the invention.

I claim:

1. In apparatus for the application of a paste-like material containinga gas, two piston-equipped cylinders disposed in axial relation, apiston rod interconnecting said pistons, a common end wall between saidcylinders and equipped with a check valve permitting flow of paste-likematerial in only one direction, fluid pressure means coupled to one ofsaid pistons for reciprocating the same, a flow port in each cylinderspaced from said common end wall, the flow port in one cylinder servingas an inlet and the flow port in the other cylinder sewing as an outlet,a check valve in the inlet flow port permitting flow of paste-likematerial only into the associated cylinder, a check valve in the pistonof the inlet flow port-equipped cylinder permitting flow of paste likematerial only toward said common end wall, and means coupled to saidreciprocation means for varying the stroke of the interconnected pistonas a function of the compressibility of the paste-like material, thepiston in the outlet flow portequipped cylinder being a hollow ram, theinterior of which is coupled to said fluid pressure means, said ram alsoproviding a portion of the end wall of its associated cylinder, the endwall so provided being opposite said common wall.

2. In apparatus of the character described, a cylinder equipped with apiston movably mounted therein, said piston being equipped with a checkvalve, a flow portequipped with an inlet check valve at one end of saidcylinder, said inlet check valve being operative to permit flow ofmaterial only to said cylinder, an outlet at the other end of saidcylinder, a check valve-equipped barrier intermediate the ends of saidcylinder, said check valveequipped barrier defining a pair of chamberswithin said cylinder, a piston rod connected to said piston andextending through said check valve-equipped barrier, said piston rodincluding a hollow ram in the portion of said cylinder between saidcheck valve-equipped barrier and said other end, a fluid pressure systemcoupled to the hollow inside of said ram for varying the pressure insideof said ram and operative to reciprocate said piston, and meansresponsive to the stroke of said ram and operatively connected to saidsystem for adjusting the stroke of said ram.

3. In apparatus of the character described, a cylinder equipped at oneend with a check valve permitting flow of material only into saidcylinder, said cylinder being equipped with a hollow ram movable throughthe wall at the other end thereof, a transverse wall in said cylinderintermediate the ends thereof and equipped with a check valve, :1 pistonrod attached to said ram and extending through said transverse wall,said piston rod carrying a piston on the side of said wall remote fromsaid ram, said piston being equipped with a check valve, an outlet insaid cylinder adjacent said ram, said check valves all being operativeto permit material flow toward said outlet, a seal in the other end wallabout said ram, and a fluid pressure system coupled to said ram forpressurizing the interior of said ram to move said ram and said pistonsimultaneously and relative to said transverse wall.

4. In apparatus of the character described, two cylinders disposed inaxial relation, a common end wall between said cylinders and equippedwith a check valve permitting flow of material only from one of the twocylinders to the other, the said one cylinder being equipped with pistonmeans and the other cylinder being equipped with hollow ram means, apiston rod connecting said piston means and ram means, said piston rodextending through said common wall, fluid pressure means coupled to theram means in said other cylinder for pressurizing the interior and forreciprocating the same, an outlet in said one cylinder remote from saidcommon wall, an inlet in said one cylnider in the end thereof oppositesaid common end wall, a check valve in said one cylinder inletpermitting flow of paste-like material only into said one cylinder, acheck valve in the piston means of said one cylinder permitting flow ofmaterial only toward said common end wall, and means coupled to saidreciprocating means for varying the stroke of said ram means.

5. In apparatus of the character described, an elongated casingproviding a closed-ended casing providing a cylinder at one end, apiston slidably mounted in said cylinder, a piston rod attached to saidpiston, an intermediate transerse wall in said casing, said piston rodextending through said transverse wall, said transverse wall in one endwall of said casing providing the end wall of said cylinder, checkvalves in said piston and cylinder end walls all operative to permitmaterial flow only toward the other end of said casing, an outlet at theother end of said casing, the other end wall of said casing beingapertured, a hollow ram slidingly, sealingly mounted in the aperturethereof and coupled to said piston rod, said ram being thermallyconductive, and means for introducing pressurized fluid into said ram tomove said ram and piston simultaneously and relative to saidintermediate transverse wall.

6. In apparatus for the application of a paste-like material containinga gas, two cylinders disposed in axial relation and each equipped withpiston means, a piston rod interconnecting said piston means, a commonend wall between said cylinders and equipped with a check valvepermitting flow of paste-like material in only one direction, a flowport in each cylinder spaced from said common end wall, the flow port inone cylinder serving as an inlet and the flow port in the other cylinderserving as an outlet, a check valve in the inlet flow port permittingflow of paste-like material only into the cylinder equipped with saidinlet flow port, a check valve in the piston means of the inlet flowport-equipped cylinder permitting flow of paste-like material onlytoward said common end wall, fluid pressure means coupled to the pistonmeans in the outlet flow port-equipped cylinder for reciprocating thepiston means therein, said coupled piston means having a Kendall June17, 1890 Prott Nov. 12, 1907 10 Lower Oct. 29, 1935 Rotter Nov. 15, 1938Kitsman Mar. 23, 1943 Cartier Mar. 10, 1953 FOREIGN PATENTS GreatBritain July 13, 1955

